boost question.

Buck toenges · 11-07-2003, 10:36 AM

O.k. I have had the turbo s checked out. Leak down cylinder 1=3% drop, 2cylinder = 2% drop, 3 cylinder= 3% drop, 4 cylinder=3% drop. Compression #1= 145lbs, #2=145lbs, #3=140lbs, #4=140lbs. Two leaks 1 at pressure relief valve at oil filter. 2 at back of cam housing. Round gasket with tabs. Both are minor. Finally the boost tops out at 1.1 at 3700 rpm. This seems low. What do you guys think about this data?

Lawrence Coppari · 11-07-2003, 01:11 PM

The comprression has nothing to do with the boost. I suspect a vacuum leak somewhere that is not allowing your turbo to spool up properly.

Check all those little vacuum line to start with. Make sure they are all connected. Let us know what you find.

Buck toenges · 11-07-2003, 01:48 PM

The leak down and compression figures were just there for your comments. I don't think they had anything to do with the boost. I would like to know what you guys think of everything but especially the "low" boost

Lawrence Coppari · 11-07-2003, 02:32 PM

I already did. Check the vacuum lines. They control the boost - assuming your boost gauge is correct.

Boost should be 1.8 bar on gauge. If not, something is wrong. Probably what controls turbo which is vacuum.

awilson40 · 11-08-2003, 03:32 AM

1.2 on the stock gauge is also 'boost protection mode'
do a search on 'blink codes' and check them to see if you have a fault
throwing you into 'limp home mode'

ronin · 11-08-2003, 06:14 PM

Quote:

Originally posted by awilson40
1.2 on the stock gauge is also 'boost protection mode'
do a search on 'blink codes' and check them to see if you have a fault
throwing you into 'limp home mode'

no blinky on the 86. wasn't available until 88

Wolf1 · 11-08-2003, 06:17 PM

Quote:

Originally posted by ronin
no blinky on the 86. wasn't available until 88

So what is the magical, mystical, profound procedure for retrieving these blinky codes?..

ronin · 11-08-2003, 06:21 PM

on the late 88s and up you use the Porsche shop diagnostic tool. there is also a blink code tester available but Britwrench told me that it wasn't worth a squat

Wolf1 · 11-08-2003, 06:31 PM

So the average guy like me, with the average tools like Snap-on scanner, Tech-1, Tech-2, Star tester, DRB-III, and sun scope & emission machine is just out of luck? I guess I was hoping for: jumper this wire to that wire and count the little flashy's.....

ronin · 11-08-2003, 06:33 PM

well, tellyawhaddimgonnado. before I put my foot in my mouth I'll check the manual as I am not 100% sure. lemme see what I can find out

Wolf1 · 11-08-2003, 06:39 PM

cool

Wolf1 · 11-08-2003, 06:40 PM

Thanks.

ronin · 11-08-2003, 06:43 PM

well, the manual says that the DME from a m.y. 88 S is capable of self diagnosis using the Porsche 9268 diagnostic tool. but the blink code function wasn't available until 91 when Calif. legislated that all cars must have a visual warning when emissions components malfunction

Wolf1 · 11-08-2003, 06:50 PM

Damn, so there is no way for me to check codes?

ronin · 11-08-2003, 06:57 PM

apparently not. there is a little something that I was working on by seeing whether it would be possible to re-do the DME to accept the 88 software for being able to have the diagnostics feature

robm-951 · 11-08-2003, 07:23 PM

The 86-on turbos do have the blink code test. To do this you must first drive the car untill it goes into it's safe mode (~1.2 bar) or just start and run the car if you are just checking for other faults. Then while the ignition is still on, connect a led to the test port and start counting the blinks. Once you turn the ignition off, the error codes are erased and the DME is (essentially) reset.

Danno of guru racing has an excellent write-up done on his web page. Here is the link to that write-up.

Rob

ronin · 11-08-2003, 07:45 PM

ahaaa. this is getting better by the minute. I didn't realize that you actually could get blink codes from the earlier DME. one thing to remember is to do the test while the car is still on as turning the ignition off will clear the DME

awilson40 · 11-09-2003, 03:02 AM

A common thing to throw you into protection mode is a bad TPS.
The blink coded will tell you that. Just make sure you keep it running
as the reset when ignition is turned off.
Also check for a bad cycling valve. If it's stuck or broken you will be stuck with the same low boost with no fault codes.

Mike B · 11-09-2003, 06:58 AM

Quote:

Originally posted by Buck toenges
O.k. I have had the turbo s checked out. Leak down cylinder 1=3% drop, 2cylinder = 2% drop, 3 cylinder= 3% drop, 4 cylinder=3% drop. Compression #1= 145lbs, #2=145lbs, #3=140lbs, #4=140lbs. Two leaks 1 at pressure relief valve at oil filter. 2 at back of cam housing. Round gasket with tabs. Both are minor. Finally the boost tops out at 1.1 at 3700 rpm. This seems low. What do you guys think about this data?

By the way, those are very acceptable leakdown and compression numbers.

Lawrence Coppari · 11-09-2003, 07:09 AM

I still say it's vacuum related. A ruptured diaphragm in the valve near the coolant reservoir will prevent proper boost. If the vacuum line comes off or is broken, you only get about 1.2 on your gauge. A broken diaphragm does the same thing.